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September 18, 2011

Satellite Debris Expected To Hit Earth Sept. 23

by editor

A 20-year-old defunct satellite is expected to fall to Earth sometime next week, NASA officials announced on Friday.

According to the Associated Press (AP), the U.S. space agency now predicts that the nearly seven-ton Upper Atmosphere Research Satellite (UARS) will re-enter Earth's atmosphere on September 23, plus or minus one day.

"NASA scientists have calculated the satellite will break into 26 pieces as it gets closer to Earth," the AP said. "The odds of it hitting someone anywhere on the planet are 1 in 3,200. The heaviest piece to hit the ground will be about 350 pounds, but no one has ever been hit by falling space junk in the past."

"The decommissioned satellite could land anywhere between 57 degrees north latitude and 57 degrees south latitude, a vast swath of populated territory. Predictions will only get more precise as the landing approaches," AFP reporters added in a Friday article.

More specifically, according to the International Business Times, that means that pieces of the satellite could land anywhere from just south of Juneau, Alaska, to slightly north of the tip of South America. Most of the debris is expected to burn up upon re-entry, with just about 1,200 pounds worth of the satellite surviving and covering an estimated 500-mile wide area somewhere in that region.

According to the AFP, NASA posted a brief update on its website Friday, reporting that the UARS re-entry, which had been anticipated later this month or early October, would come sooner than expected "because of a sharp increase in solar activity since the beginning of this week."

"Safety is NASA's top priority," the organization added.

As previously reported here on RedOrbit, UARS was launched on September 12, 1991. It was carried into space on board Space Shuttle Discovery (STS-48) and was deployed into orbit 3 days later.

The $750 million mission measured the concentrations and distribution of gases important to ozone depletion, climate change and other atmospheric phenomena. NASA said reading from UARS provided conclusive evidence that chlorine in the atmosphere, originating from human-produced chlorofluorocarbons, is at the root of the polar ozone hole.

"The satellite's current orbit is 155 by 174 miles (250 by 280 kilometers), with an inclination of 57 degrees, said NASA," the IB Times said. "That means the satellite would have to descend into the atmosphere somewhere between 57 degrees north latitude and 57 degrees south"

"Researchers have confirmed that no hazardous material are left in the satellite, However, they have urged people to not to touch any of the fallen parts," they added.

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Image Caption: This conceptual image shows the Upper Atmosphere Research Satellite, launched on Sept. 15, 1991, by the space shuttle Discovery. Originally designed for a three-year mission, UARS measured chemical compounds found in the ozone layer, wind and temperature in the stratosphere, as well as the energy input from the sun. Together, these measurements helped define the role of Earth's upper atmosphere in climate and climate variability. The 35-foot-long, 15-foot-diameter UARS was decommissioned on Dec. 14, 2005. Credit: NASA